Underfeed stoker



Feb. 19, 1929. 1,702,891

L. D. BURWELL UNDERFEED STOKER Filed July 15. 19 2 Sheets-Sheet 1 INVENTOR.

6 35 Lormgl] Bgrwel/ BY 9629mm ATTORNEY Feb. 19, 1929.

L. D. BURWELL UNDERFEED STOKER Filed July 15. 1920 2 Sheets-Sheet 2 INVENTOR. LormgIlBurweH BY 968 M A TTORNEYS.

Patented Feb. 19, 1929.

UNITED STATES PATENT QFFICE.

LORING D. BURWELL, OF MINNETONKA, MINNESOTA, ASSIGNOR TO WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

UNDERFEED STOKER.

Application filed July 15,

My invention relates to stokers of the mechanical type and has for its object the provision of side wall tuyeres which may be applied directly to the air passages arranged adjacent to the furnace side walls, whereby a stoker of the standard type may be rendered readily capable of burning high ash coals without undue side-wall clinkering.

In the drawings, Fig. 1 is a perspective view of one form of underfeed stoker showing my fuel-bed side-wall construction applied thereto, a portion of the walls and parts of the stoker being omitted; Fig. 2 is an elevational view of one of the tuyere plates; Fig. 2 is a 5 fragmentary view in elevation of the outer side of a tuyere plate; Fig. 3 is a sectlonal View taken along the line of 3-3 Fig. 2; Fig.

4 is an edge view of one of the plate sections;

Fig. 5 is a side elevation of a side-wall tuyere shown secured in position with respect to stoker parts shown in dot and dash lines;

Fig. 6 is a sectional view taken along the line 6 6 of Fig. 5; Fig. .7 is a perspective view of an upper tuyere bracket member; and Eig. 8 is a perspective view of a lower tuyere bracket member.

' It has been found that certain form of stokers of the underfeed type are not entirely satisfactory when Middle West bituminous coal, high in ash, is used. The principal reason for this is that clinkers develop at the side and prevent uniform combustion throughout the fuel bed area. I have found that, if tuyere constructions are arranged at the sides of the stoker and adjacent to the side walls of the furnace, the tuyere constructions being adapted to receive air from the air Ichamber below the stoker, the formation of 'clinkers will be minimized and whatever clinkers are formed may be readily broken up by agitating the fuel bed. Air in passing through thetuyere constructions not only exerts a cooling effect on the side walls, but also passes to the fuel bed to assist in combustion.

In the drawings, I show a furnace construction having side walls 2 with an underfeed stoker disposed therein and dividing the interior of the furnace construction into a combustion chamber 1 above the stoker and an air chamber 5 below the stoker.

The stoker includes marginal wall elements 6 forming lateral air passages? in communication with the air chamber 5 and intermediate pairs of wall elements 8 forming air 1920. Serial No. 396,358.

passages 9 in communication with the air chamber 5. Bottom members 10 cooperate with lower portions of marginal wall' elements6 and with lower portions of the wall elements 8 of said pairs to form retorts 11.

The intermediate passages 9 formed between wall elements 8 are covered by tuyeres 9 and the marginal passages 7 are covered by side wall tuyere constructions indicated generally at 12.

It is characteristic of my improved side wall tuyere constructions that they are supported entirely by the stoker structure and independently of the furnace side walls 2.

The side wall tuyere constructions 12 con sist of brackets 13 and tuyere means 18, the brackets being supported by the wall elements 6 and the tuyere means being carried by the brackets. Each bracket 13 is preferably made in two parts, an upper part 1 1 and a lower part 15, the upper and lower parts being provided, respectively, with flanges 16 and 17 connected together by bolts 18 and 19. The bracketparts 141 and 15 are preferably formed as angular sections with substantially vertical portions 14 and 15 respectively, and lower flange portions 14" and 15" respectively, adapted to rest on the upper edges of the marginal wall elements 6; and, the lower flange portions 1 1' and 15 are provided with openings 14 and 15, respectively, which communicate with the air passages 7. The brackets 13 are held in place with respect to the wall elements 6 by means of cross plates engaging the latter and bolts 22 pass ing through the brackets. The tuyere means 13 are held in place with respect to the brackets 13 and cooperate with the latter to form lateral air chambers 13 extending substantially above the intermediate tuyeres 9*.

Each tuyere means 13 is made in sections 25, 26, 27, 28, 29, 30, 31 and 32, the end sections 25 and being curved as shown in the drawing. Each of the sections is provided with an overhanging portion 33 whichis designed to overhang the top edge of the angle member portions 1 1 and 15 and adjacent the bottom, the intermediate plate sections are provided with lugs or members 34; designed to fit within openings 14 and 15 provided in the base portions 1 1 and 15 of the angle member and prevent lateral movement thereof as may be seen from Fig. 6. The adjacent tuyere plate sections are provided with ship-lap joints havingprqections 35 and recesses 36 cooperating therewith to define such joints. Each .upper section 25 is provided with a lug 3'? extending within the associated chamber 13 Bolts 38 having hooks 39 designed to fit over the lugs 37 pass I up through the air passages 7 andthey are fitted over the lugs 37 for the purpose of holding the upper sections 25 in place. The lower ends of the bolts 38 are threaded and receive nuts 40 which bear against angle iron sections 41 adapted to rest against the underside of the marginal side wall elements 6.

with the horizontal portions found adj acent lower end of the bracket member.

:to the lowermost end portions of the wall elements 6. The horizontal portion of the bracket is provided with a recess 45 and the lower tuyere plate section 32 is provided with a lug 46 designed to fit within the recess. It will be seen that the several tuyere plates define a side wall and are held in position by means of the interfitting parts and the bolt 38 cooperating with the lug 37. The lower section 32 rests on the horizontal portion with its lug 46 within the recess 45 and having its curved edge provided with an overhanging portion fitting about the curved edge of the The adjacent plates are provided with interfitting ship-lap joints, and these, with the overhang ing portions 33 and the lugs 34, together with the cooperating lug as and the upper lug-37 and its bolt 38 cooperate .to hold the sections in'place, and thereby present a continuous side wall surface. Each of the plates has tuyere openings 50 arranged substantially as shown'in the drawings and is ribbed at the back, as shown at 51, preferably diagonally. The sections are ribbed for the purpose of presenting a greater area of contact for the incoming air and thereby increasing the cooling efi'ect thereof. Due to the fact that the tuyere plates are made in sections, it is obvious that, should any plate be broken or burned out, a new one may be readily inserted, thereby resulting in a saving over a construction in which the entire wall was made as a single plate. For example, should it become necessary to remove and replace the plate 27 shown in Fig. 5, the plates 26 and 25 are first loosened and moved to the right as viewed in the drawing, the new plate 27 is put in place and the plates 26 and 25 are then replaced in their original positions. Furthermore, there beingsufiicient space therefor, the plate sections may expand and contract due to changes in temperature without liability ofcracks developing.

" The tuyere plates are provided with tuyere openings of sufficient size or number to render an entire side wall section capable of delivering a volume of air substantially equal to about one-half the quantity delivered by an intermediate tuyere section, thereby insuring that combustion will be uniform through the fuel bed.

From the foregoing description of my invention the operation thereof will be readily understood, that is, air enters through the side-wall air box and passes through the tuyeres for the purpose of supporting combustion and for the purpose of cooling the surface of contact thereof with the fuel bed, thus lowering the temperature thereof to such a degree that clinkers in contacttherewith will be rendered brittle and thereby readily capable of being broken up because of agita tion by certain of the reciprocating elements of the stoker. The maintenance of the surface of contact of the tuyere plates at a low temperature is furthermore facilitated by a provision of the ribs in the rear thereof in order to increase the area of metal in contact with the air, thereby increasing the degree of radiation. It will also be apparent from the foregoing that my improved tuyere constructions are supported entirely by the stc-ker structure and independently of the furnace sidewalls adjacent to which they may be disposed. Due to the particular construcition of the brackets and the formation of the tuyere means in plate sect-ions, the tuyere means maybe readilyv removed or replaced.

While Ihave shown my invention in but one form, it will be obvious to those skilled in'the art that it is not so limited, but is susceptible of various other changes and modifications, without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

WhatI claim is 1. The. combination with the side wall air box of a mechanical'stoker having substantially inclined and horizontal portions, of a bracket provided with substantially horizontal and inclined portions to fit corresponding 7 portions of the air box, means to secure the bracket in position, the horizontal base portion of said bracket being provided with a recess and plate sections provided with tuyeres having portions overhanging the bracket, the lower section having a substantially horizontal portion fitting the corresponding portion of the bracket and provided with alug fitting within said recess, the upper section havinga lug, and fastening means carried by the air box, and cooperating with the lug, the adjacent edges of the plate sections being provided with ovei'rlapping joints.

2. A fuel-bed side-wall air box for use in connection with stokers, comprising a bracket having a vertical back Wall portion and a base portion extending at right angles thereto, the lower end of the base portion being inclined to a major portion thereof in order to be horizontal when the side wall air box is in position, the ends of the vertical back wall portion being curved, and tuyere plates having flanges overhanging the edgeof the vertical back wall portion, the upper and lower plates having their edges curved to lit the cooperating curved edges of the vertical back wall portion, the upper tuyere plate having a lug projecting within the interior of the box for attachment by an appropriate n1ember,and the other plates having lugs fitting within the openings within the base portion of the bracket.

3. A foraminated tuyere member adapted for use in a progressive fuel feed stoker for a furnace having side Walls, comprisng a platelike body portion, a hook-like overhanging supporting portion provided on the upper part of the member, an anchoring lug provided on the lower portion, and lateral lap joint portions provided on the member so that when assembled in place with other tuyere members in the stoker smooth surfaced ship-lap joints are formed with adjacent members along the fuel contacting surface thereof with the overlapping side of the member remote in the direction of fuel feed.

4. In a furnace, a unitary underfeed stoker structure dividing the furnace into combustion and air chambers and including substantially vertical marginal wall elements and pairs of intermediate wall elements, bottom wall members extending between the marginal wall elements and the adjacent wall elements of the adjoining pairs and between the several pairs to form retorts, said well elements defining air passages in communication with said air chamber, tuyeres supported by the upper edges of the intermediate pairs of wall elements and bridging the passages defined thereby, bracket means supported independently of the furnace side walls by said marginal wall elements and having wall portions extending upwardly from said wall elements, tuyere means formed separately from said marginal wall elements and bracket means and cooperating with the upwardly extending wall portions of the latter to define air chambers extending above the normal zone of clinker formation and communicating with the furnace chamber by passages provided by said tuyere means, and means for detachably securing the tuyere means in proper position with respect to the marginal Wall elements and the bracket means.

5. In a multiple retort furnace a system of tuyere structures with fuel retorts between them and air boxes beneath the tuyere structures formed by the retort sides, there being an air box formed between the extreme retort and the furnace side wall, and the extreme tuyere structure adjacent the side wall consisting of an integral L-shape frame member with its horizontal arm apertured and spanning and resting on the sides of the extreme air box, and its vertical arm arranged adjacent the side wall, and separate tuyere members extending upwardly and outwardly from the lower-inner to the upper-outer portion of such L-shape member and engaged over such upper-outer portion thereof.

In testimony whereof, I have hereunto subscribed my name this 9th day of July, 1920.

LORING n. BURWELL. 

